bisecting fixing commit since fb683b5e3f53a73e761952735736180939a313df building syzkaller on 1508f45368a309a3b1196a342b3d64ce7be4cc43 testing commit fb683b5e3f53a73e761952735736180939a313df with gcc (GCC) 8.1.0 kernel signature: 18679d5d23373a31f28878724124b8afa2f7d08fb500f61a31613e613fe7dc5d all runs: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname testing current HEAD 399849e4654ea496a6217ba4e5ee3d304c995ab4 testing commit 399849e4654ea496a6217ba4e5ee3d304c995ab4 with gcc (GCC) 8.1.0 kernel signature: 6ec288832e0bac9450b815740e75038c1ecdc6702cfe904155090451bd09db2c run #0: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #1: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #2: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted run #4: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #5: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #6: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #7: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #8: crashed: KASAN: null-ptr-deref in llcp_sock_getname run #9: crashed: KASAN: null-ptr-deref in llcp_sock_getname revisions tested: 2, total time: 24m33.708237065s (build: 16m19.235255215s, test: 7m47.196290438s) the crash still happens on HEAD commit msg: Linux 4.19.131 crash: KASAN: null-ptr-deref in llcp_sock_getname IPv6: ADDRCONF(NETDEV_CHANGE): team0: link becomes ready IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready IPv6: ADDRCONF(NETDEV_UP): veth0_to_hsr: link is not ready IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_team: link becomes ready ================================================================== BUG: KASAN: null-ptr-deref in memcpy include/linux/string.h:373 [inline] BUG: KASAN: null-ptr-deref in llcp_sock_getname+0x341/0x440 net/nfc/llcp_sock.c:531 BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 Read of size 43 at addr 0000000000000000 by task syz-executor.4/7441 PGD 85fb9067 P4D 85fb9067 PUD 933c2067 PMD 0 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 7441 Comm: syz-executor.4 Not tainted 4.19.131-syzkaller #0 CPU: 1 PID: 7444 Comm: syz-executor.5 Not tainted 4.19.131-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x177 lib/dump_stack.c:118 RIP: 0010:memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:55 kasan_report_error mm/kasan/report.c:352 [inline] kasan_report.cold.9+0x6d/0x309 mm/kasan/report.c:412 Code: 90 90 90 90 eb 1e 0f 1f 00 48 89 f8 48 89 d1 48 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8 48 89 d1 a4 c3 0f 1f 80 00 00 00 00 48 89 f8 48 83 fa 20 72 7e 40 38 fe RSP: 0018:ffff888085f8fcf0 EFLAGS: 00010246 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 RAX: ffff888085f8fe12 RBX: 000000000000002b RCX: 000000000000002b memcpy+0x23/0x50 mm/kasan/kasan.c:302 RDX: 000000000000002b RSI: 0000000000000000 RDI: ffff888085f8fe12 memcpy include/linux/string.h:373 [inline] llcp_sock_getname+0x341/0x440 net/nfc/llcp_sock.c:531 RBP: ffff888085f8fd10 R08: ffffed1010bf1fc8 R09: ffffed1010bf1fc2 R10: ffffed1010bf1fc7 R11: ffff888085f8fe3c R12: ffff888085f8fe12 __sys_getpeername+0x123/0x220 net/socket.c:1735 R13: 0000000000000000 R14: ffff8880803ef580 R15: 0000000000000000 FS: 00007f8c44103700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000009317f000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __do_sys_getpeername net/socket.c:1748 [inline] __se_sys_getpeername net/socket.c:1745 [inline] __x64_sys_getpeername+0x6e/0xb0 net/socket.c:1745 memcpy include/linux/string.h:373 [inline] llcp_sock_getname+0x341/0x440 net/nfc/llcp_sock.c:531 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe __sys_getpeername+0x123/0x220 net/socket.c:1735 RIP: 0033:0x45a6f9 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ff050879c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000034 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a6f9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff05087a6d4 R13: 00000000004c1430 R14: 00000000004d5658 R15: 00000000ffffffff __do_sys_getpeername net/socket.c:1748 [inline] __se_sys_getpeername net/socket.c:1745 [inline] __x64_sys_getpeername+0x6e/0xb0 net/socket.c:1745 ================================================================== do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a6f9 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f8c44102c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000034 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a6f9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f8c441036d4 R13: 00000000004c1430 R14: 00000000004d5658 R15: 00000000ffffffff Modules linked in: CR2: 0000000000000000